FEASIBILITY DEMONSTRATION OF PYROLYTIC GRAPHITE COATED NOZZLES.
Abstract
The objective of this program is to demonstrate the feasibility of pyrolytic graphite coatings for use in uncooled solid propellant rocket nozzles under very severe operating conditions. The excellent serviceability of pyrolytic graphite coatings in 1/2-inch diameter nozzles was demonstrated in prior work with propellants having flame temperatures from 5500 to 6500F. In the current work, nozzles of 1.1-inch and 2.3-inch diameter are to be tested with a 6500F propellant. Delamination cracks in coatings deposited on the sub-scale nozzle inserts continued to be a problem. In the second sub-scale motor test, a 66-mil coating was completely removed during the 83-second firing duration. Coating failure by edge spalling was again indicated. A continuing effort is being made, including work on full-scale inserts, to eliminate the cracking problem. Stress analyses of both free-standing and composite cylinders were carried out to define the effects of geometric variables, but no stresses were found to satisfactorily explain the observed cracks. More involved stress analysis is under consideration. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Aug 18, 1964
- Accession Number
- AD0605422
Entities
People
- James D. Batchelor
Organizations
- ARCO